PET measurement of rCBF has a successful history as a tool in neuroscience. Mapping regions of altered blood flow in response to neural activity provides an anatomical representation of brain function in-vivo. Evolutionary improvements of blood flow tracers are required to accommodate the increasing sophistication and sensitivity of functional activation studies. This research project will develop the radiotracer Fluoromethane labeled with 17F(t1/2 = 64 s) [17F]CH3F for measurement of rCBF using PET and functional activation protocols. The short half-life of 17F combined with the potential for less invasive procedures make this inert gas an ideal candidate. Several methods for the production of [17F]CH3F will be explored. High yields, rapid chemistry and low contaminates are the optimizing criteria. PET scans will be performed on primates using inhaled [17F]CH3F and simple activation paradigms. Concurrent studies using [15O]H2O and identical activation paradigms are planned. The statistical analysis of the rCBF data will consist of a direct comparison between the new rCBF tracer [17F]CH3F and [15O](H2O or CO2 ).